I was recently investigating this and the question of audio came up. I'm still confused about it, but I've solved the problem by demanding that what needs to be played must be supplied as a file. I can then set up a uniform playback method.

Some installers I know say display port doesn't have audio (again, I'm still confused and it might be Thunder or Lightning)(no joke -- who comes up with these names?). Someone at Apple says it has audio, but it depends on what you connect it to.

(In my application we had to supply video to a Roland video switch that doesn't handle audio, and, separately, send analog audio to an analog PA mixer.)

If you could clarify the audio situation, that would be a help!

Thank you.